Our invention pertains to a retarder speed control system and particularly to such control systems to regulate car speeds in automatic railroad classification yards.
As the requirement for more fully automated operation of railroad classification yards has developed, new concepts for the operation of retarders have become necessary. A closer and more accurate control of the coupling speed of cars in the storage tracks is desirable and in fact required in order to reduce the damage to the cars and to their loads. Conversely, less stalling of the classified cars short of coupling with other cars already in the selected storage track is required in order to reduce the amount of trimming operations necessary to assemble trains. One change to accomplish this more accurate control has been to add a short tangent point retarder in each storage track beyond the final routing switch for that track where the rails begin the tangent, that is, straight stretch of storage area. The final speed control to achieve the desired coupling speed is executed in this retarder. Another change is incorporated in the speed control operation exercised by the other retarders preceding the final storage track switch, that is, such master, intermediate, and group retarders as may be used. It has become apparent that it is desirable to use these retarders less to control the ultimate coupling speed of the car in the storage track but rather to control speed to retain a separation between the various cuts of cars moving in the yard in order to provide correct switching for selected routing purposes. This of course improves the yard operation by reducing misroutes of the cuts while allowing a constant humping speed.
Said in other words, the initial retarders in the yard are used to minimize the variance in the average speed of the cars moving between the crest of the hump yard and their selected storage tracks. A major aim in all this improvement is for a smooth and continuous flow of cars over the yard hump at a predetermined rate in cars per minute which will result in optimum efficiency for the yard operation.
Accordingly, an object of our invention is an improved retarder speed control arrangement for automatic classification yards.
Another object of the invention is an improved retarder control for classification yards to obtain consistent average cut speeds between the hump and the bowl tracks and better coupling operations.
It is also an object of our invention to provide an improved automatic classification yard speed control system to minimize misroutes of cars and reduce errors in coupling speeds.
Still another object of our invention is a method of controlling the speed of free rolling cars in railroad classification yards by a series of retarders between the hump crest and a selected storage track to insure proper coupling of the moving cars with cars previously routed into the selected track.
Yet another object of our invention is a method of operation of a railroad classification yard by which the speed of the car cuts is controlled through a series of retarders along the selected route to obtain predetermined average running times between the hump and the entrance to the selected storage track and by controlling coupling speed with a final retarder at the entrance of the storage track operated in accordance with the track and car parameters.
It is also an object of the invention to control car speed in a classification yard so as to maintain equal spacing between cuts of cars moving from the hump crest to the bowl tracks through the master, intermediate, and group retarders.
Yet another object of our invention is a speed control arrangement for automatic classification yards which maintains relatively unchanged the time spacing between centers of successive cuts of cars while moving past any two locations along their corresponding routes from crest to bowl.
A still further object of the invention is an improved speed control system for classification yards in which master, intermediate, and group retarders are used to obtain a predetermined running time for a car from the crest to a selected bowl storage track and a tangent point retarder is used to assure proper coupling with cars previously stored in the selected track.
Another object of the invention is a control arrangement for tangent point retarders in a classification yard which determines the release time of the retarder for a cut of cars to achieve a computed exit speed in accordance with the predicted speed reduction which will be obtained by the braking force of the closed retarder on the cut and the drag force of the open retarder on the cut.
Still another object of our invention is a method of control for tangent point retarders in a classification yard by which the required exit speed to achieve a predetermined coupling speed is determined in accordance with selected cut and storage track rolling parameters and the retarder is controlled to obtain that exit speed in accordance with the combined cut speed reduction resulting from both closed and open retarder positions.
Also an object of our invention is a control system for railroad classification yards including two or more retarders along each route between the yard crest and the storage tracks to control the speed of cars to achieve predetermined average running times to obtain a maximum humping rate and to minimize misroutes due to catch-up of successive cuts and a final tangent point retarder in each storage track to control the speed of the car as it moves through the storage track to assure coupling to previously stored cars within a selected coupling speed range.
Other objects, features, and advantages of our invention will become apparent from the following specification and appended claims when taken in connection with the accompanying drawings.